1. Field of the Invention
This invention relates to the field of sanding tools and more particularly to a particle collecting sander which both removes and collects particles from a sanded surface.
2. Description of Art
For as long as sanding devices have been used to smooth surfaces, there has existed a need to collect the particular matter created as a result of the sanding operation. Traditionaly, sanding/particle collection was done as a two step manual process. In an attempt to combine sanding and collecting into a single operation, various tools were developed.
U.S. Pat. No. 2,499,933--Smul shows a device which combines a vacuum cleaner attachment and a sanding tool wherein the sanding tool is provided with a plurality of openings. The sanding tool is mounted inside the opening of the vacuum cleaner attachment in order that dust and removed material can be carried off by suction through the openings and a gap provided between the outer edges of the sanding tool and the interior edges of the vacuum attachment. U.S. Pat. No. 4,062,152--Mehrer also shows a combination vacuum/sanding tool where a plurality of openings are provided in a backing plate which is covered by a pourous adhesive sheet. U.S. Pat. No. 4,549,371--Hakoda shows a vacuum/sanding tool wherein the apparatus for creating a negative pressure is mounted within the tool itself. A number of suction passages are provided through a sandpaper engaging layer which passages are alligned with line holes in the sandpaper. Hakoda also provides a number of channels formed in the sandpaper engaging layer to create a number of openings on the outer edges of the layer.
Each of the above described tools suffer from similar problems. Since a negative pressure cannot be created across the surface of the sanding material, particle collection efficiency is minimized. It would appear that collection efficiency could be improved by increasing the negative pressure applied to the various openings. However, as negative pressure is increased, the above tools will have a tendency to stick to the surface being sanded requiring a greater force to move the tool. Increasing the force required to move the sanding tool becomes a significant drawback, especially in manual labor operations. Increasing the force requires a greater effort on the part of the laborer which will inevitably result in a reduced work period.
A further problem comes into play when devices such as U.S. Pat. No. 4,062,152 use pourous abrasive material, namely the clogging of pores in the material with particulate matter. Such clogging reduces significantly the sanding efficiency of the device. One solution to this problem is to replace the material, another is to remove and clean the material. Neither of these solutions presents an acceptable alternative.
A still futher problem associated with collecting/sanding tools is that it is not economically feasible to reuse the sanded material. For example in a spakle-sanding operation, once dried and sanded spakle particles can be reused. Up to now, however, collection efficiency has not been capable of recovering a sufficient amount of material.
U.S. Pat. No. 3,826,045--Champayne is mentioned only because it shows the use of a hollow handle to apply a negative pressure in a dust collection operation.